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Coils and Transmission Lines.
NOW AVAILABLE ** New Program "TRANCO_1.exe"
This program analyses performance as a transmission line, of a single-layer solenoid coil which may be inserted in an antenna wire. The coil itself may be used as a very short vertical antenna at its 1/4-wave resonant frequency. From the input data of length, diameter and number of turns, the program calculates inductance, capacitance and resistance of the equivalent transmission line. The secondary constants of characteristic impedance Zo, phase shift, velocity factor, and attenuation are calculated. Also the feedpoint input impedance, R+jX, for when a coil is used as an antenna. Because of the sensitivity to the environment of such an antenna and its high Q it will be necessary to trim antenna length to a particular wanted resonant frequency. Download TRANCO_1 in a few seconds from website below and run immediately. Filesize = 38 Kbytes. (It's at the bottom of the list.) ---- .................................................. .......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. .......... |
Coils and Transmission Lines.
To satisfy demands for disclosure of the source code of my programs I
have made the source code of program TRANCO_1 available from my website. It may be of interest to antagonists in the "current through coils" civil war. The source code text, which is almost readable using non-proportional spaced text readers, can be found in "Download Pascal source code from here" section on the Index page. ---- .................................................. .......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. .......... |
Coils and Transmission Lines.
Reg Edwards wrote:
It may be of interest to antagonists in the "current through coils" civil war. The nature of traveling wave current and standing wave current is different. Does your program take that into account? The "current through coils" argument boils down to the ones who understand standing wave currents in a standing wave antenna and those who refuse to take the time to understand. Quoting "Optics", by Hecht: "E(x,t) = 2Eo*sin(kx)*cos(wt) This is the equation for a STANDING or STATIONARY WAVE, as opposed to a traveling wave (Fig. 7.10). Its profile does not move through space. ... [The phase] doesn't rotate at all, and the resultant wave it represents doesn't progress through space - it's a standing wave." Until the gurus take the time to understand the nature of standing waves in standing waves antennas, they will keep committing the same mental blunders over and over. -- 73, Cecil http://www.qsl.net/w5dxp |
Coils and Transmission Lines.
Cecil Moore wrote:
Reg Edwards wrote: It may be of interest to antagonists in the "current through coils" civil war. The nature of traveling wave current and standing wave current is different. Does your program take that into account? The "current through coils" argument boils down to the ones who understand standing wave currents in a standing wave antenna and those who refuse to take the time to understand. Quoting "Optics", by Hecht: "E(x,t) = 2Eo*sin(kx)*cos(wt) This is the equation for a STANDING or STATIONARY WAVE, as opposed to a traveling wave (Fig. 7.10). Its profile does not move through space. ... [The phase] doesn't rotate at all, and the resultant wave it represents doesn't progress through space - it's a standing wave." Until the gurus take the time to understand the nature of standing waves in standing waves antennas, they will keep committing the same mental blunders over and over. Hecht forgot to put the phase difference in his formula. It's no wonder there's no phase information in your standing waves, Cecil, Hecht left it out. Not only that, but where did he get the idea that it was sin(kx) instead of cos(kx). I understand Hecht is a good old boy, but I'd like to see his derivations. 73, Tom Donaly, KA6RUH |
Coils and Transmission Lines.
"Cecil Moore" wrote in message
Until the gurus take the time to understand the nature of standing waves in standing waves antennas, they will keep committing the same mental blunders over and over. -- 73, Cecil http://www.qsl.net/w5dxp More astonishing than that, Until the "gurus" put their finger on the coil, or aquarium thermometer, or RF ammeter, or infrared scope and see that the loading coil (in a typical quarter wave resonant whip) is heating up at the bottom, being the reality that defies their "scientwific theories why it shouldn't" - they will keep committing the same mental blunders over and over. What's next? There is less current in a wire (coil) where wire (coil) gets hotter? Let the games begin! Thermometers don't lie, meters don't lie, even EZNEC shows it! So wasaaaaap? Yuri, K3BU |
Coils and Transmission Lines.
Yuri Blanarovich wrote: More astonishing than that, Until the "gurus" put their finger on the coil, or aquarium thermometer, or RF ammeter, or infrared scope and see that the loading coil (in a typical quarter wave resonant whip) is heating up at the bottom, being the reality that defies their "scientwific theories why it shouldn't" - they will keep committing the same mental blunders over and over. Yuri, No one I have seen has every said one tuern can't get hotter than another turn in a loading coil. For example, I can take a piece of airdux and short a single turn anywhere in the coil. That turn and the turns around it will get very hot, often even melting the form and discoloring the wire, even with modest power applied in a resoant circuit. I had my 75 watt Novice rig melt miniductor in certain spots way back in the very early 60's. The problem is wild theories are created from small grains of truth or factoids. It is the wild theories that people question. In an effort to support the wild claims, there seems to be an effort to dismiss anything but the wild theories. Here is how it goes: 1.) My Hustler antenna loading coil (known to be a poor electrical design) melted the heatshrink at the bottom 2.) This must be becuase there is only high current at the bottom of every loading coil. 3.) This must be because the standing waves on the antenna all wind up in the loading coil. 4.) This must mean all loading coils act just like they are the x degrees of antenna they replace. 5.) This is why, no matter what we do with loading coil Q, efficiency doesn't change much. 6.) We will write a IEEE paper about this astounding fact, since all the texbooks about loading coils or inductors in general must be wrong 7.) Anyone who point out it is imperfections in the design of the system that cause this must be wrong, since I saw the coil get hot 8.) Anyone who disagrees with me must think himself a guru, and be incapable of learning or understanding how things work 9.) I know all this because the bottom of the coil gets hot in my antenna What's next? There is less current in a wire (coil) where wire (coil) gets hotter? Thermometers don't lie, meters don't lie, even EZNEC shows it! So wasaaaaap? It's all been explained over and over again. If the termination impedance of the coil is very high compared to shunting impedances inside the coil to the outside world, a coil can have phase shift in current at each terminal and it can have uneven current distribution. This is not caused by standing waves or "electrical degrees" the coil replaces, but rather by the displacement currents which can provide a path for the through currents. Reg actually explained this very well, as has Roy, Tom D, Gene, Tom ITM, Ian, and a half dozen others. The reason you keep beating your head against the wall is you want to think the conclusions you formed were correct. If I wanted to design a loading coil that has virtually 100% current taper, I could. If I wanted to design one with virtually no taper, I could. I could actually have an antenna of a fixed height and by making various styles of loading coils go anywhere from nearly uniform distribution at each end of the coil to some significant taper. The problem is Cecil attributes it all to standing waves, and not to the inductor's design. You seem to be doing the same. Since we won't agree with your wrong theories, you then conclude we are saying step one is wrong and you never saw what you saw. Step one is fine. Step two is where everything you say falls apart. 73 Tom |
Coils and Transmission Lines.
Yuri Blanarovich wrote:
"Cecil Moore" wrote in message Until the gurus take the time to understand the nature of standing waves in standing waves antennas, they will keep committing the same mental blunders over and over. -- 73, Cecil http://www.qsl.net/w5dxp More astonishing than that, Until the "gurus" put their finger on the coil, or aquarium thermometer, or RF ammeter, or infrared scope and see that the loading coil (in a typical quarter wave resonant whip) is heating up at the bottom, being the reality that defies their "scientwific theories why it shouldn't" - they will keep committing the same mental blunders over and over. What's next? There is less current in a wire (coil) where wire (coil) gets hotter? Let the games begin! Thermometers don't lie, meters don't lie, even EZNEC shows it! So wasaaaaap? If you're looking for an argument, you're looking in the wrong place. Nobody denies the raw evidence, like the fact that some loading coils get hotter at the bottom than at the top... and the fact that some other coils don't (or nowhere near as much). There are good explanations for everything you see. But the only valid explanations are the ones that account for *all* the facts about *all* types of loading coils. The argument is specifically about Cecil's attempts to explain the evidence, using his own particular ideas about "standing wave antennas". He makes it kinda work for the cases he wants to think about, but in other cases it gets things fundamentally wrong - and that isn't good enough. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Coils and Transmission Lines.
Reg Edwards wrote:
To satisfy demands for disclosure of the source code of my programs I have made the source code of program TRANCO_1 available from my website. It may be of interest to antagonists in the "current through coils" civil war. The source code text, which is almost readable using non-proportional spaced text readers, can be found in "Download Pascal source code from here" section on the Index page. ---- .................................................. ......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. ......... There is no "Download Pascal source code from here" section on the Index page. There is a "Get Pascal source code from here" section which lists the following: GRNDWAV3.pas * Groundwave propagation vs frequency, distance and terrain. TOPHAT2.pas * Performance of top-capacitance loaded vertical. PADMATCH.pas * T and Pi resistive-matching and minimum loss pads. I do not see the TRANCO_1 source code listed. 73 John |
Coils and Transmission Lines.
On Sun, 2 Apr 2006 12:07:38 -0400, "Yuri Blanarovich"
wrote: Thermometers don't lie, meters don't lie, even EZNEC shows it! So wasaaaaap? Hi Yuri, That's a good question. The last you had to say, two years ago, was you were waiting for the snow to melt to provide a better measure. It must have been a particularly long and cold winter these two years. 73's Richard Clark, KB7QHC |
Coils and Transmission Lines.
Tom Donaly wrote:
Hecht forgot to put the phase difference in his formula. It's no wonder there's no phase information in your standing waves, Cecil, Hecht left it out. You are mistaken. If Hecht left it out then so did Gene Fuller. I suggest you listen to Gene when he says: Regarding the cos(kz)*cos(wt) terms in the standing wave equation: Gene Fuller, W4SZ wrote: In a standing wave antenna problem, such as the one you describe, there is no remaining phase information. Any specific phase characteristics of the traveling waves died out when the startup transients died out. Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. The only "phase" remaining is the cos (kz) term, which is really an amplitude description, not a phase. Not only that, but where did he get the idea that it was sin(kx) instead of cos(kx). I understand Hecht is a good old boy, but I'd like to see his derivations. Apparently, you are ignorant of the difference in conventions between optics and RF engineering. In optics, there is no current so there is no current changing phase at an open circuit. In optics, the M-field changes directions but not phase. In RF engineering, a change in direction of the H-field is considered to be a 180 degree phase shift. Both conventions are correct as long as one understands them. Your strange statement about Hecht above just proves your ignorance. -- 73, Cecil http://www.qsl.net/w5dxp |
Coils and Transmission Lines.
On Sun, 2 Apr 2006 09:02:46 +0100, "Reg Edwards"
wrote: The source code text, which is almost readable using non-proportional spaced text readers, can be found in "Download Pascal source code from here" section on the Index page. Hi Reggie, A fine example of coding. 73's Richard Clark, KB7QHC |
Coils and Transmission Lines.
Ian White GM3SEK wrote:
The argument is specifically about Cecil's attempts to explain the evidence, using his own particular ideas about "standing wave antennas". He makes it kinda work for the cases he wants to think about, but in other cases it gets things fundamentally wrong - and that isn't good enough. That's just not true, Ian. If the distributed network model agrees with the lumped circuit model, then the lumped circuit model is being used in an appropriate situation. If the distributed network model disagrees with the lumped circuit model, then the lumped circuit model is being used in an inappropriate situation. The distributed network model is always right when it disagrees with the lumped circuit model. The distributed network model is a *superset* of the lumped circuit model. To quote Dr. Corum: "Distributed theory encompasses lumped circuits and always applies." And before you dismiss Dr. Corum as a "crackpot", as others have, please pay attention to the references for his peer-reviewed paper published by the IEEE: Kraus, Terman, Ryder, Ramo & Whinnery, Born & Wolf. The problem is that the lumped circuit model is being used in inappropriate situations because you and others do not understand how standing wave current in standing wave antennas differs from traveling wave current in traveling wave antennas. To compound the error, none of you are willing to discuss it from a technical standpoint. That unwillingness reeks of religion, not science. Someone we both know and respect wonders why you are so closed minded. I suggested he contact you by email. If you, or anyone else, were willing to discuss the nature of standing waves from a technical standpoint, most of the present argument would be resolved by that discussion. I'm willing to discuss it. Why aren't you? It is entirely possible that I am abusing the distributed network model, but nobody will be able to prove it unless they engage in a discussion of standing waves. -- 73, Cecil http://www.qsl.net/w5dxp |
Coils and Transmission Lines.
Cecil Moore wrote:
Tom Donaly wrote: Hecht forgot to put the phase difference in his formula. It's no wonder there's no phase information in your standing waves, Cecil, Hecht left it out. You are mistaken. If Hecht left it out then so did Gene Fuller. I suggest you listen to Gene when he says: Regarding the cos(kz)*cos(wt) terms in the standing wave equation: Gene Fuller, W4SZ wrote: In a standing wave antenna problem, such as the one you describe, there is no remaining phase information. Any specific phase characteristics of the traveling waves died out when the startup transients died out. Phase is gone. Kaput. Vanished. Cannot be recovered. Never to be seen again. The only "phase" remaining is the cos (kz) term, which is really an amplitude description, not a phase. Not only that, but where did he get the idea that it was sin(kx) instead of cos(kx). I understand Hecht is a good old boy, but I'd like to see his derivations. Apparently, you are ignorant of the difference in conventions between optics and RF engineering. In optics, there is no current so there is no current changing phase at an open circuit. In optics, the M-field changes directions but not phase. In RF engineering, a change in direction of the H-field is considered to be a 180 degree phase shift. Both conventions are correct as long as one understands them. Your strange statement about Hecht above just proves your ignorance. Whatever. I'd still like to see his derivations. In your case, you're using the wrong equation anyway. What you really want is Beta*l, or the radian length of your transmission line. You can get that if you know, or can measure the usual parameters in the transmission line impedance equation, using that equation to solve for Beta*l. That won't prove your theory because you still haven't shown that any one transmission line model is unique in terms of substituting for your coil, but at least it'll give you something to do. 73, Tom Donaly, KA6RUH |
Coils and Transmission Lines.
wrote in message oups.com... Yuri Blanarovich wrote: More astonishing than that, Until the "gurus" put their finger on the coil, or aquarium thermometer, or RF ammeter, or infrared scope and see that the loading coil (in a typical quarter wave resonant whip) is heating up at the bottom, being the reality that defies their "scientwific theories why it shouldn't" - they will keep committing the same mental blunders over and over. Yuri, No one I have seen has every said one tuern can't get hotter than another turn in a loading coil. For example, I can take a piece of airdux and short a single turn anywhere in the coil. That turn and the turns around it will get very hot, often even melting the form and discoloring the wire, even with modest power applied in a resoant circuit. I had my 75 watt Novice rig melt miniductor in certain spots way back in the very early 60's. Stop right here. We are talking about perfectly good coil (Hustler 80m resonator) no shorts between the turns, ne end effect shorting out turns (and if so, then both ends are the same). Perfectly good coil, with wire insulation intact, uniformly wound, uniform wire diameter (constant resistance) good insulation, until wire gets red hot, and covered with what appears to be heat shrink tubing. When I applied about 600W to it, the coil obviously started to overhead, with obvious tapered patter of heat distribution (no shorted turn culprit) with most intense on the bottom, slowly tapering towrds the top. No signs of similar "melting" at the top (to blame "shorted" turn from the top cap), nor anywhere in the middle to indicate shorted turn. If you do not believe that this could happen, than say so and I will provide the evidence, I will melt another coil. If you believe and can relate some of your melting to mirror this case, than please explain what else can cause this besides the current being SIGNIFICANTLY higher at the bottom than at the top. What I know from the thermodynamics, that heat rises to the top. If the current was (almost) equal, then the coil would be heating up and starting to melt uniformly, with actually more pronounced effect at the top, due to the rising and adding heat from the lower part of the coil (no upside Buick here). So lets talk specifics of the argument and not detours, please! The problem is wild theories are created from small grains of truth or factoids. It is the wild theories that people question. I question reality that I experienced, claims to the contrary ("it can't be") and theories rode in support of pro and con. In an effort to support the wild claims, there seems to be an effort to dismiss anything but the wild theories. Here is how it goes: 1.) My Hustler antenna loading coil (known to be a poor electrical design) melted the heatshrink at the bottom Maybe poor electrical design, but perfectly sound coil, with uniform insulated wire, wound on perfect cylinder. It was Hustler coil with its physical properties and heatshrink tubing over the turns that magnified the effect and attracted my attention. 2.) This must be becuase there is only high current at the bottom of every loading coil. I will disregard the rest of your post as a irrelevant crap, typical of your prior riding in on a high horse, ridiculing and pontificating. If you can stay on the technical side of the discussion we will continue, if you can't, then play the "guru" and we are all "stay stoooopid"! Yuri 3.) This must be because the standing waves on the antenna all wind up in the loading coil. 4.) This must mean all loading coils act just like they are the x degrees of antenna they replace. 5.) This is why, no matter what we do with loading coil Q, efficiency doesn't change much. 6.) We will write a IEEE paper about this astounding fact, since all the texbooks about loading coils or inductors in general must be wrong 7.) Anyone who point out it is imperfections in the design of the system that cause this must be wrong, since I saw the coil get hot 8.) Anyone who disagrees with me must think himself a guru, and be incapable of learning or understanding how things work 9.) I know all this because the bottom of the coil gets hot in my antenna What's next? There is less current in a wire (coil) where wire (coil) gets hotter? Thermometers don't lie, meters don't lie, even EZNEC shows it! So wasaaaaap? It's all been explained over and over again. If the termination impedance of the coil is very high compared to shunting impedances inside the coil to the outside world, a coil can have phase shift in current at each terminal and it can have uneven current distribution. This is not caused by standing waves or "electrical degrees" the coil replaces, but rather by the displacement currents which can provide a path for the through currents. Reg actually explained this very well, as has Roy, Tom D, Gene, Tom ITM, Ian, and a half dozen others. The reason you keep beating your head against the wall is you want to think the conclusions you formed were correct. If I wanted to design a loading coil that has virtually 100% current taper, I could. If I wanted to design one with virtually no taper, I could. I could actually have an antenna of a fixed height and by making various styles of loading coils go anywhere from nearly uniform distribution at each end of the coil to some significant taper. The problem is Cecil attributes it all to standing waves, and not to the inductor's design. You seem to be doing the same. Since we won't agree with your wrong theories, you then conclude we are saying step one is wrong and you never saw what you saw. Step one is fine. Step two is where everything you say falls apart. 73 Tom |
Coils and Transmission Lines.
"Ian White GM3SEK" wrote in message ... Yuri Blanarovich wrote: "Cecil Moore" wrote in message Until the gurus take the time to understand the nature of standing waves in standing waves antennas, they will keep committing the same mental blunders over and over. -- 73, Cecil http://www.qsl.net/w5dxp More astonishing than that, Until the "gurus" put their finger on the coil, or aquarium thermometer, or RF ammeter, or infrared scope and see that the loading coil (in a typical quarter wave resonant whip) is heating up at the bottom, being the reality that defies their "scientwific theories why it shouldn't" - they will keep committing the same mental blunders over and over. What's next? There is less current in a wire (coil) where wire (coil) gets hotter? Let the games begin! Thermometers don't lie, meters don't lie, even EZNEC shows it! So wasaaaaap? If you're looking for an argument, you're looking in the wrong place. Nobody denies the raw evidence, like the fact that some loading coils get hotter at the bottom than at the top... and the fact that some other coils don't (or nowhere near as much). So what is the reason? Isn't the higher current through the same resistance wire cause of more heat development? We now why and Cecil explained it. Depends where the coil is placed in the antenna and its place on the cosine current distribution curve. It has been shown epxerimentally and also by EZNEC when modeled properly as solenoid or loading stub. Yea, the "other" zero size coils don't show that, EZNEC confirms that. There are good explanations for everything you see. But the only valid explanations are the ones that account for *all* the facts about *all* types of loading coils. We are talking about typical loading coils in typical antennas, no need to go to "all" that would skew that and "prove" it ain't so. The argument is specifically about Cecil's attempts to explain the evidence, using his own particular ideas about "standing wave antennas". He makes it kinda work for the cases he wants to think about, but in other cases it gets things fundamentally wrong - and that isn't good enough. As far as I see, it is not just Cecil's own idea or discovery, he attempted to explain the obvious effect and in the process found that there is more support and standing wave theory by others. So we have an effect, and (close enough) explanation and way of modeling it (close enough), but have a bunch of people that cling to "she's flat". Yuri, K3BU/m -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Coils and Transmission Lines.
Tom Donaly wrote:
Whatever. I'd still like to see his derivations. "Optics", by Hecht, 4th edition, page 289. The intensity of a light beam is associated with the E-field so Hecht's equations are in relation to the E-field. Speaking of the light standing wave: "The composite disturbance is then: E = Eo[sin(kt+wt) + sin(kt-wt)] Applying the indentity sin A + sin B = 2 sin 1/2(A+B)*cos 1/2(A-B) E(x,t) = 2*Eo*sin(kx)*cos(wt)" Hecht says the standing wave "profile does not move through space". I have said the RF standing wave current profile does not move through a wire. Hecht says the standing wave phasor "doesn't rotate at all, and the resultant wave it represents doesn't progress through space - it's a standing wave." I have said the same thing about the RF standing wave current phasor. Hecht says the standing wave transfers zero net energy. I have said the same thing about RF standing waves. -- 73, Cecil http://www.qsl.net/w5dxp |
Coils and Transmission Lines.
Yuri Blanarovich wrote:
It has been shown epxerimentally and also by EZNEC when modeled properly as solenoid or loading stub. Yea, the "other" zero size coils don't show that, EZNEC confirms that. As a data point, the results of modeling a coil as a lumped inductor Vs a helical coil are NOT the same in EZNEC. EZNEC disagrees with itself. I am much more inclined to trust the helically modeled inductance than the lumped inductance. As Dr. Corum says: "Distributed theory encompasses lumped circuits and always applies." In other words, the Distrubuted network model is a superset of the lumped circuit model. -- 73, Cecil http://www.qsl.net/w5dxp |
Coils and Transmission Lines.
"Richard Clark" wrote in message ... On Sun, 2 Apr 2006 12:07:38 -0400, "Yuri Blanarovich" wrote: Thermometers don't lie, meters don't lie, even EZNEC shows it! So wasaaaaap? Hi Yuri, That's a good question. The last you had to say, two years ago, was you were waiting for the snow to melt to provide a better measure. It must have been a particularly long and cold winter these two years. 73's Richard Clark, KB7QHC No, but I got cut off the NG by AOL's dropping NGs and therefore lost touch with the severity of the problem. Also got too busy with real life, which I considered more important and didn't even dream that this still would be the problem. I though that some of the unbelievers would by now done it, saw it, realized they were wrong and confessed. Apparently not. So I am glad to be still around and will try to either get educated or contribute to setting the record straight and correct the fallacies that are out there. Sooo, nobody would try to do the experiment and SEE it, but rather keep chasing the gay electron phasors charged with Kirchoffs through three way intersections and blame Bush for it? Yuri, K3BU.us |
Coils and Transmission Lines.
Cecil Moore wrote:
The argument is specifically about Cecil's attempts to explain the evidence, using his own particular ideas about "standing wave antennas". He makes it kinda work for the cases he wants to think about, but in other cases it gets things fundamentally wrong - and that isn't good enough. That's just not true, Ian. If the distributed network model agrees with the lumped circuit model, then the lumped circuit model is being used in an appropriate situation. If the distributed network model disagrees with the lumped circuit model, then the lumped circuit model is being used in an inappropriate situation. The distributed network model is always right when it disagrees with the lumped circuit model. The distributed network model is a *superset* of the lumped circuit model. To quote Dr. Corum: "Distributed theory encompasses lumped circuits and always applies." And before you dismiss Dr. Corum as a "crackpot", as others have, I don't intend to - that quotation is perfectly correct. It means that in a test-case situation where the lumped model *does* apply, the distributed model will give EXACTLY the same results. This is the test case that I'm trying to make you apply, to check that with a lumped-inductance load, your antenna theory predicts the correct behaviour, namely no phase shift in the current through a lumped inductance. There's no problem with the distributed circuit model. There's no problem with the lumped circuit model as a subset of that. All the problems are with your incorrect application of those models. The underlying problem is that you don't see the difference. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Coils and Transmission Lines.
Ian White GM3SEK wrote:
I don't intend to - that quotation is perfectly correct. It means that in a test-case situation where the lumped model *does* apply, the distributed model will give EXACTLY the same results. Ian, you know nothing is "EXACTLY" the same. All you can say is that the two models give acceptably similar results within a certain range of accuracy. To paraphrase Roger Whittaker: "'EXACTLY' is for Children Spinning Daydreams". This is the test case that I'm trying to make you apply, to check that with a lumped-inductance load, your antenna theory predicts the correct behaviour, namely no phase shift in the current through a lumped inductance. :-) That's like proving there's no loss in a lossless transmission line, Ian. Please send me a 100 uH lumped inductance and I will run some tests on it and report back to you. What do you want to bet the lumped circuit model will be wrong? Some people have a problem with their model trying to dictate reality. You seem to have fallen into that trap. Allow me to raise my voice. THERE IS NO SUCH THING IN REALITY AS A LUMPED INDUCTANCE!!!! The lumped circuit model is an approximation to reality. It has been patched numerous times as situations came up that it could not handle. Sometimes it works and sometimes it doesn't work. Since the distributed network model is a superset of the lumped circuit model, if there is ever any disagreement between the two models, the distributed network model wins every time. The test is not whether the distributed network model yields the same results as the lumped circuit model. The test is whether the lumped circuit model yields the same results as the distributed network mode. That's what the argument is all about. The distributed network model is the GOLD standard. The lumped circuit model is just a pale approximation to reality. There's no problem with the distributed circuit model. There's no problem with the lumped circuit model as a subset of that. All the problems are with your incorrect application of those models. That may be true, but we will never know until you (and others) recognize the difference between standing wave current and traveling wave current as explained in my other posting. But in case you missed it, here is a one wavelength dipole fed 1/4 WL from the right end. ///// is a 90 degree loading coil. ------A------B-/////-D-------------fp------------- The current at B is measured by an RF ammeter at one amp. The current at D is measured by a similar RF ammeter at zero amps. I can provide an EZNEC model if you like. How does your lumped circuit model explain those measured results? -- 73, Cecil http://www.qsl.net/w5dxp |
Coils and Transmission Lines.
On Sun, 2 Apr 2006 17:49:30 -0400, "Yuri Blanarovich"
wrote: Sooo, nobody would try to do the experiment and SEE it, but rather keep chasing the gay electron phasors charged with Kirchoffs through three way intersections and blame Bush for it? Visit: http://www.powerloafing.com/home/ and select the first offering Bush Goes Powerloafing W: Carl, this is really nice cubicle you've got here. I work in a oval. That's a cubicle with -uh- oval corners. Rove: OK hand it over (waiting for W to surrender the bottle of hooch) Rove: Not until after your second term. All of it! (taking the bottle and a bag of white substance) W: You're such a buzz-kill. There's also a great episode of Cubicle Carl done as a Star Trek segment. 73's Richard Clark, KB7QHC |
Coils and Transmission Lines.
Cecil Moore wrote:
Ian White GM3SEK wrote: I don't intend to - that quotation is perfectly correct. It means that in a test-case situation where the lumped model *does* apply, the distributed model will give EXACTLY the same results. Ian, you know nothing is "EXACTLY" the same. All you can say is that the two models give acceptably similar results within a certain range of accuracy. NO! Reality is not on trial here. We are examining your model which is attempting to describe reality. In a test case where the loading is DEFINED to be lumped inductance only, agreement with the lumped-circuit model must be mathematically EXACT. If one model is a true subset of the other, then as we come closer and closer to the idealized test case, all the extra terms in the bigger model will tend to zero leaving only the subset model. In the limit, the agreement is indeed exact. (For example, to take up your earlier mis-statement, circuit theory for DC is a true subset of circuit theory for AC/RF. Set "w" (omega) to zero and you're left with only the DC relationships. But there is no discontinuity - as w gets smaller and smaller there is no sudden jump to a whole new theory. When w is exactly zero, we expect exact mathematical agreement with DC theory... and of course we get it.) We do not expect any real-life loading coil to behave exactly like a lumped inductance, so we cannot physically construct a perfect test case. But we can envisage a perfect test case in order to test the model; and for that, we are entitled to demand exact results. I'm sorry, but all this is Scientific Method 101. Most people don't need to understand this stuff in detail; though if they do, most people can also appreciate the compelling logic of it. You have put yourself in a position where you do need to understand scientific logic in some detail, and follow the rules that logic lays down... but you don't. This is the test case that I'm trying to make you apply, to check that with a lumped-inductance load, your antenna theory predicts the correct behaviour, namely no phase shift in the current through a lumped inductance. :-) That's like proving there's no loss in a lossless transmission line, Ian. Please send me a 100 uH lumped inductance and I will run some tests on it and report back to you. What do you want to bet the lumped circuit model will be wrong? Some people have a problem with their model trying to dictate reality. You seem to have fallen into that trap. Allow me to raise my voice. THERE IS NO SUCH THING IN REALITY AS A LUMPED INDUCTANCE!!!! No, of course there isn't. It is either an approximation or - as in this case - a simplified situation that we can use to check whether theories make sense. Remember, it is your theory that we're trying to test. The challenge is for you to show that your particular application of the distributed circuit model works correctly. In a test case where the loading coil comes closer and closer to behaving like a lumped circuit, your model must do the same as all successful distributed models do. All the complications must drop away, giving closer and closer agreement to the behaviour of an antenna loaded by pure inductance only. In the limit where the loading is pure lumped inductance, the agreement must be mathematically EXACT. I am sure this can be done using a standing wave analysis for a coil-loaded antenna. I am equally sure that you have not achieved that. -- 73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
Coils and Transmission Lines.
Cecil Moore wrote:
Tom Donaly wrote: Whatever. I'd still like to see his derivations. "Optics", by Hecht, 4th edition, page 289. The intensity of a light beam is associated with the E-field so Hecht's equations are in relation to the E-field. Speaking of the light standing wave: "The composite disturbance is then: E = Eo[sin(kt+wt) + sin(kt-wt)] Applying the indentity sin A + sin B = 2 sin 1/2(A+B)*cos 1/2(A-B) E(x,t) = 2*Eo*sin(kx)*cos(wt)" Hecht says the standing wave "profile does not move through space". I have said the RF standing wave current profile does not move through a wire. Hecht says the standing wave phasor "doesn't rotate at all, and the resultant wave it represents doesn't progress through space - it's a standing wave." I have said the same thing about the RF standing wave current phasor. Hecht says the standing wave transfers zero net energy. I have said the same thing about RF standing waves. If it's a solution to the wave equation it's o.k., Cecil, but Hecht is still not using the case where there is a phase difference between the two waves. If it isn't in the original equation it won't be in the final version since they're just two ways of saying the same thing. That's fine because it's the wrong equation anyway for what you want, which involves impedances and length, which you probably don't want to deal with because you're probably under the impression they're just virtual and not real, and so not worthy of inclusion in your theory. 73, Tom Donaly, KA6RUH |
Coils and Transmission Lines.
Cecil Moore wrote:
Yuri Blanarovich wrote: It has been shown epxerimentally and also by EZNEC when modeled properly as solenoid or loading stub. Yea, the "other" zero size coils don't show that, EZNEC confirms that. As a data point, the results of modeling a coil as a lumped inductor Vs a helical coil are NOT the same in EZNEC. EZNEC disagrees with itself. I am much more inclined to trust the helically modeled inductance than the lumped inductance. As Dr. Corum says: "Distributed theory encompasses lumped circuits and always applies." In other words, the Distrubuted network model is a superset of the lumped circuit model. There is no "helically modeled inductance" in Corum's work. They specifically state that there is none. Instead, they use a substitute, which Reg does, too, and develop their theory from there. Has it ever occurred to you, Cecil, that just as lumped circuit analysis may not be appropriate for everything due to its underlying assumptions, that circuit theory may fail because you can't always reduce the electrical world to current, voltage and length? When are you going to consider field theory in your analysis, Cecil? It might come in handy in any attempt to understand something as complex as a three dimensional coil. 73, Tom Donaly, KA6RUH |
Coils and Transmission Lines.
Tom Donaly wrote:
If it's a solution to the wave equation it's o.k., Cecil, but Hecht is still not using the case where there is a phase difference between the two waves. Yes, he is, Tom. The phase *disappears* when you add the two traveling waves. That you don't recognize that fact of physics is the source of your misconception. The forward and reflected wave phasors are rotating in opposite directions at the same angular velocity. That makes their sum a constant phase value for half the cycle and the opposite constant phase value for the other half of the cycle. I and Richard Harrison have already explained that a number of times quoting Kraus and Terman. Here are a number of problems. I(f) is forward current and I(r) is reflected current. Please everybody, perform the following phasor additions where I(f)+I(r) is the *standing wave current*: I(f) I(r) I(f)+I(r) 1 amp at 0 deg 1 amp at 0 deg _________________ 1 amp at -30 deg 1 amp at +30 deg _________________ 1 amp at -60 deg 1 amp at +60 deg _________________ 1 amp at -90 deg 1 amp at +90 deg _________________ 1 amp at -120 deg 1 amp at +120 deg _________________ 1 amp at -150 deg 1 amp at +150 deg _________________ 1 amp at -180 deg 1 amp at +180 deg _________________ If you guys will take pen to paper and fill in those blanks you will uncover the misconception that has haunted this newsgroup for many weeks. If you need help with the math, feel free to ask for help. -- 73, Cecil http://www.qsl.net/w5dxp |
Coils and Transmission Lines.
Tom Donaly wrote:
When are you going to consider field theory in your analysis, Cecil? That's a fair question, Tom. The answer is just as soon as someone comes up with an example for which the distributed network model fails. We have plenty of examples where the lumped circuit model fails but not one example yet that the distributed network model won't handle. -- 73, Cecil http://www.qsl.net/w5dxp |
Coils and Transmission Lines.
Cecil Moore wrote:
(snip) Here are a number of problems. I(f) is forward current and I(r) is reflected current. Please everybody, perform the following phasor additions where I(f)+I(r) is the *standing wave current*: I(f) I(r) I(f)+I(r) 1 amp at 0 deg 1 amp at 0 deg 2 A @ 0 deg 1 amp at -30 deg 1 amp at +30 deg 1.72 A @ 0 deg 1 amp at -60 deg 1 amp at +60 deg 1 A @ 0 deg 1 amp at -90 deg 1 amp at +90 deg 0 A @ 0 deg 1 amp at -120 deg 1 amp at +120 deg 1 A @ 180 deg 1 amp at -150 deg 1 amp at +150 deg 1.72 A @ 180 deg 1 amp at -180 deg 1 amp at +180 deg 2 A @ 180 deg If you guys will take pen to paper and fill in those blanks you will uncover the misconception that has haunted this newsgroup for many weeks. If you need help with the math, feel free to ask for help. What misconception? That all current in a standing wave has the same phase, rather than one of two possible phases? |
Coils and Transmission Lines.
John Popelish wrote:
What misconception? That all current in a standing wave has the same phase, rather than one of two possible phases? The misconception is not yours, John. W7EL used that current to try to measure the phase shift through a coil and so did W8JI who came up with an unbelievable 3 nS. -- 73, Cecil http://www.qsl.net/w5dxp |
Coils and Transmission Lines.
Cecil Moore wrote:
Tom Donaly wrote: If it's a solution to the wave equation it's o.k., Cecil, but Hecht is still not using the case where there is a phase difference between the two waves. Yes, he is, Tom. The phase *disappears* when you add the two traveling waves. That you don't recognize that fact of physics is the source of your misconception. The forward and reflected wave phasors are rotating in opposite directions at the same angular velocity. That makes their sum a constant phase value for half the cycle and the opposite constant phase value for the other half of the cycle. I and Richard Harrison have already explained that a number of times quoting Kraus and Terman. Here are a number of problems. I(f) is forward current and I(r) is reflected current. Please everybody, perform the following phasor additions where I(f)+I(r) is the *standing wave current*: I(f) I(r) I(f)+I(r) 1 amp at 0 deg 1 amp at 0 deg _________________ 1 amp at -30 deg 1 amp at +30 deg _________________ 1 amp at -60 deg 1 amp at +60 deg _________________ 1 amp at -90 deg 1 amp at +90 deg _________________ 1 amp at -120 deg 1 amp at +120 deg _________________ 1 amp at -150 deg 1 amp at +150 deg _________________ 1 amp at -180 deg 1 amp at +180 deg _________________ If you guys will take pen to paper and fill in those blanks you will uncover the misconception that has haunted this newsgroup for many weeks. If you need help with the math, feel free to ask for help. Cecil, if you don't put any phase information in your original formula it won't be there when you say the same thing some other way. But if you do put it in there, then it has to affect both formulas. If it disappears, you've done something wrong. If you and Harrison can't figure out how to extract phase information from a standing wave you should return your diplomas to wherever you got them from. 73, Tom Donaly, KA6RUH (P.S. Let me give you a hint: first you have to find out what phase means in a standing wave on a transmission line. You probably already think you know, though, so I don't expect you to bother much about it.) |
Coils and Transmission Lines.
Tom Donaly wrote:
If it disappears, you've done something wrong. There is no phase information in standing wave phase, Tom. I can't find it, Gene fuller can't find it, Eugene Hecht can't find it, and James Clerk Maxwell can't find it. Any and all phase information in the standing wave phase disappears during superposing. Let me give you another example. Assume that we superpose one amp of DC current flowing in one direction and one amp of DC current flowing in the other direction. What does the superposed amplitude tell us about the amplitudes of the superposed currents? Nothing, except they were equal. -- 73, Cecil http://www.qsl.net/w5dxp |
Coils and Transmission Lines.
Cecil Moore wrote:
Tom Donaly wrote: If it disappears, you've done something wrong. There is no phase information in standing wave phase, Tom. I can't find it, Gene fuller can't find it, Eugene Hecht can't find it, and James Clerk Maxwell can't find it. Any and all phase information in the standing wave phase disappears during superposing. Let me give you another example. Assume that we superpose one amp of DC current flowing in one direction and one amp of DC current flowing in the other direction. What does the superposed amplitude tell us about the amplitudes of the superposed currents? Nothing, except they were equal. Your idea of phase is to compare amplitudes at two separate places on the same wave and noting the time difference in behavior. You're right, you get the same "phase" if you do that to a standing wave in a lossles medium. You're not right, however, in thinking that the phase difference between two waves travelling in different directions down a transmission line can never be known. But as I wrote before, that isn't what you should be after. You should want to know the Beta*l of the coil on your antenna so you'll know its electrical length. And you can know it if it is true that you can model a coil as a simple transmission line. That's a big if, but it's something you should have thought of before you shot off your mouth. 73, Tom Donaly, KA6RUH |
Coils and Transmission Lines.
Tom Donaly wrote:
You should want to know the Beta*l of the coil on your antenna so you'll know its electrical length. The discussion is no longer about coils. It's clear that a lot of posters don't understand the nature of standing waves. If they don't understand standing waves in a transmission line or on a wire, they cannot possibly understand standing waves on a coil. -- 73, Cecil http://www.qsl.net/w5dxp |
Coils and Transmission Lines.
Tom Donaly, KA6RUH wrote:
""---first you have to find out what phase means in a standing wave transmission line." Cecil knows very well what phase means in a transmission line. Terman describes it best for me, but it would be best to have his book with all his diagrams which makes his explanation of how standing waves are established simple indeed. Terman writes on page 89 of his 1955 edition: "Transmission line with Open-Circuited Load." (This is related to the standing-wave antenna which also ends up with an open-circuit load.) "When the load impedance is infinite, Eq.(4-14) (This gives the reflection coefficient rho as the vector ratio of the reflected wave to the incident wave at the load) shows that the coefficient of reflecftion will be 1 on an angle of zero. Under these conditions the incident and reflected waves (voltages) will have the same phase. As a result, the voltages of the two waves add arithmetically so that at the load E1 = E2 = EL/2. (Voltage doubles at the open circuit.) Under these conditions it follows from Eqs. (4-8) (Eforward/Iforward=Zo) and (4-11) (Ereflected / Ireflected=-Zo) that the currents of the two waves are equal in magnitude but opposite in phase; they thus add up to zero load current, as must be the case if the load is open-circuited. Consider now how these two waves behave as the distance l from the load increases. The incident wave advances in phase beta radians per unit length, while the reflected wave lags correspondingly; at the same time magnitudes do not change greatly when the attenuation-constant alpha is small. The vector sum of the voltages of the two waves is less than the arithmetic sum, as illustrated in Fig. 4-3a, for l=lambda/8. This tendency continues until the distance to the load becomes exactly a quarter wavelength, i.e.,until beta l = pi/2. The incident wave has then advanced 90-degrees from its phase position at the load, while the reflected wave has dropped back a similar amount. The line voltage at this point is thus the arithmertic difference of the voltages of the two waves, as shown in Fig. 4-3a, for l=lambda/4 and it will be quite small if the attenuation is small. The resultant voltage will not be zero, however, because some attenuation will always be present, and this causes the incident wave to be larger and the reflected wave to be smaller at the quarter-wave length point than at the load, where the amplitudes are exactly the same." This is enough of Terman`s desctiption to establish the pattern of SWR. He describes simply but not too simply. Almost anything anyone would want to know is in the book. The illustrations are worth thousands of words. Anytime I have any doubt about radio, Terman can straighten me out. Best regards, Richard Harrison, KB5WZI |
Coils and Transmission Lines.
Cecil Moore wrote:
Tom Donaly wrote: You should want to know the Beta*l of the coil on your antenna so you'll know its electrical length. The discussion is no longer about coils. It's clear that a lot of posters don't understand the nature of standing waves. If they don't understand standing waves in a transmission line or on a wire, they cannot possibly understand standing waves on a coil. Well, Cecil, you've certainly shown your knowledge is weak in this area. You can improve the general knowledge by being the first to crack the books. 73, Tom Donaly, KA6RUH |
Coils and Transmission Lines.
Tom Donaly wrote:
Cecil Moore wrote: The discussion is no longer about coils. It's clear that a lot of posters don't understand the nature of standing waves. If they don't understand standing waves in a transmission line or on a wire, they cannot possibly understand standing waves on a coil. Well, Cecil, you've certainly shown your knowledge is weak in this area. You can improve the general knowledge by being the first to crack the books. The nature of standing waves is not a difficult subject. Some people have a single particular misconception about standing waves that have lead them to technically incorrect conclusions about standing wave antennas. In fact, before I brought up the subject, it appeared they didn't even realize that a mobile antenna is a standing wave antenna. Given a lossless, unterminated transmission line, with two black boxes located at points along the line. Source-----------a-BBox-b-------------c-BBox-d-----------open The current at 'a' is one amp and the current at 'b' is zero The current at 'c' is zero and the current at 'd' is one amp What's in the black boxes? -- 73, Cecil http://www.qsl.net/w5dxp |
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